Chiusi-Chianciano Terme station, in the "new" town of Chiusi Scalo, is a major stop on the main Rome-Florence line (which passes through Arezzo) and is also the terminus of a secondary line that originates in Siena (13 trains daily; 80 min.). A short bus ride will carry you up to the centro storico.
From Montepulciano, follow the SS146. From Florence, take the A1 to the Chiusi exit. From Siena, take the SS326 toward Sinalunga to the A1 south to the Chiusi exit. You can park off Via della Pietriccia and Via dei Longobardi.
Because Chiusi has one of the main train stations in the region, most towns run several LFI buses (www.lfi.it) here daily. Sixteen buses depart daily from Montepulciano (50 min.) that stop in Chianciano Terme (25 min.) along the way. Eight daily buses connect Chiusi's center with Sarteano. Ask to get off at the centro storico or you'll end up in the meatpacking town of Chiusi Scalo down below.
The best way to see the land of the Etruscans up close is by bike, specifically by riding a bicycle path called the Sentiero della Bonifica that stretches about 60km (37 miles) between Chiusi and Arezzo. It crosses historic bridges and passes friendly farms that offer a true taste of the region. The gravelly path is better suited for mountain bikes and hybrids than for fancy road bikes, and can be an arduous trek under the hot sun. For more instructions and for a good map, see www.sentierodellabonifica.it.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.